Extra Roof Trim for Unvented Attic

[D725A]

We have to get a new roof soon for our 1924 colonial in NY. We plan on an unvented attic as per buildingscience.com etc. Part of that will require above roof deck insulation of about 2 inches of rigid polyiso foam boards. I understand that usually the roofer puts the boards on the existing deck then 3/4 plywood on top of that and screws down into the rafters and decking.

Due to the added 2.75 inches from the boards and plywood, the eave fascias will have to be replaced. And I guess the trim or fascia by the rake (gable walls) will also have to be replaced or expanded. On the rake I wanted to know if it is big job to raise the fascia and also replace the aluminum trim installed there at the time the house added vinyl siding. Is Is this all fairly simple for a roofer to do?

 

[joecaption]

There's several ways this could be done.
All new coil stock could be installed that would be wider, not a cheap job because there's going to be a lot of waisted material. With A normal fashia you can get 3, pieces out of every section cut off the roll. Since it's wider you can only get 2, the rest is trashed.

A much simpler way would be to simply add vinyl baseboard moulding upside down. It would cover that gap, look good, never need painting, simple to install, it will extend the shingles out more so there's less chance of black stain on the fashias from dirt running off the roof.
Make sure they add drip cap as there install the new roof.
It would act like shingle moulding but would be wide enough to cover the gap. You may want to rip it so it's not as wide if all you can find is 5-1/4" base.

 

[D725A]

Thanks for the info (but your link brings you to a sports site--something wrong there.)

 

[nealtw]

All I would do is ripp 2x4 to 2 3/4" and add the top of all the facial and add 1x4 facia or the vinyl that Goe talked about in front of that. Your roofer should be able to look after all of this.

 

[pathweaver]

Depending on the pitch of the roof and how hard the downpours in your area can get, it might be simpler and cheaper to install a large drip edge. This is an angled piece of metal that gets installed under the roof and covers the upper-back of the gutter, forcing rainwater into the gutter and not behind it.

I know most roofers will do this, while only some roofers will offer professional installations of eavestrough/fascia.

This is a simple process and doesn't include much material so should be rather cheap (2-3$ per linear ft).

 

[D725A]

Thanks for the idea. I just noticed in the attic that the original fascia has a one-inch gap that is covered by the white aluminum coil--presumably the drip edge installed when the new gutters were put in a few years ago. A roofer type told me that's fairly common as that the roof line does not always run straight. perhaps since 1924 there has been shifting or wood shrinkage. So you're saying that a wider aluminum drip edge would be structurally adequate in acting as a wood fascia.

Just to update those who were kind enough to respond to my question, i am now leaning towards not putting any rigid foam insulation above the roofline. if I fur out the rafters below--which is usually advisable to make sheetrocking easier--I can get up to 7inches of insulation, which with half inch sheetrock would bring me to almost R28--with thermal bridging much reduced.

 

[nealtw]

Leave an air gap above the insulation so air can travel from soffit to ridge vents.

 

[D725A]

Neal this is a sealed attic, there are currently no soffit or ridge vents nor is it the plan to put them in. The idea is to put enough insulation/sealing under the rafters to prevent any winter condensation under the roof deck. Also important to make sure we keep any moisture out of the attic via bathroom exhaust maybe even an ERV attached to our AC.

thanks.

 

[nealtw]

There you go, I will just shut up now.